This invention relates to sprinkler guards for protecting sprinkler heads, especially those having thermally responsive elements.
Fire protection sprinklers normally include a thermally responsive element designed to release a closure to permit water to be passed through the sprinkler when the temperature exceeds a selected level and a deflector to distribute the water. The thermally responsive element may, for example, be a glass bulb or a eutectic solder composition normally maintaining an assembly of components which support a cap so as to prevent release of water through the sprinkler head. Such thermally responsive elements and sprinkler deflectors may be subject to damage or destruction if struck by objects being moved in the vicinity of the sprinkler head.
Heretofore, sprinkler guards in the form of wire cages have been mounted on a sprinkler head, either before or after the head is assembled to a water supply line, but such prior art arrangements have certain disadvantages. In the patent to Gray et al. U.S. Pat. No. 3,797,746, for example, a sprinkler guard assembled from wire members is mounted on a sprinkler head by two of the wire members which embrace the sprinkler head in the region adjacent to the threaded portion by which the sprinkler head is mounted in a threaded receptacle. The wire members form two opposed loops which engage oppositely directed flat surfaces on the sprinkler head arranged to receive a wrench for use in mounting the sprinkler head in a threaded receptacle.
Consequently, with this arrangement it is necessary to mount the sprinkler head in a threaded receptacle connected to a water line before the sprinkler guard can be affixed to the head. This requires the guard to be assembled to the head when the head is in an inconvenient position adjacent to a ceiling, for example, or disposed over storage racks.
The Fenske et al. U.S. Pat. No. 5,632,339 discloses a sprinkler guard which avoids the foregoing problem by providing a sprinkler head having a special structure which includes a first region adjacent to the threaded end of the sprinkler head which is shaped to receive a wrench to mount the sprinkler in a threaded receptacle and a second region on the opposite side of the first region from the threaded end which is designed to receive a base portion of a sprinkler guard. With this arrangement, a sprinkler guard can be assembled to a sprinkler head before the head is mounted in a threaded receptacle of a water line but, in order to accomplish this, a specially designed sprinkler head is required.